(function () {

	var Event = YAHOO.util.Event,
		Dom = YAHOO.util.Dom,
		Lang = YAHOO.lang,
		UA = YAHOO.env.ua,
		ContextMenu = YAHOO.widget.ContextMenu,		

		MenuPrototype = YAHOO.widget.Menu.prototype,
		fnMenuInitDefaultConfig = MenuPrototype.initDefaultConfig,

		// The currently focused MenuItem label, or the MenuItem label that can be focused 
		// by the user.

		m_oCurrentItemLabel,
		

		// Private constants for strings
		
		_ARIA_PREFIX = "aria-",
		_HAS_POPUP = "haspopup",
		_ROLE = "role",
		_PRESENTATION = "presentation",
		_MENUITEM = "menuitem",
		_HREF = "href",
		_SUBMENU = "submenu",
		_MENU = "menu",
		_MENUBAR = "menubar",
		_LABELLED_BY = "labelledby",
		_FOCUS = "focus", 
		_BLUR = "blur",
		_ITEM_ADDED = "itemAdded",
		_USE_ARIA = "usearia"
		_TRIGGER = "trigger";


	// Menu ARIA plugin		

	var setARIARole = function (element, role) {
	
		element.setAttribute(_ROLE, role);
	
	};


	var setARIAProperty = function (element, property, value) {

		element.setAttribute((_ARIA_PREFIX + property), value);
	
	};


	var addHasPopupRole = function (element) {
	
		if (element.nodeType === 1) {
			setARIAProperty(element, _HAS_POPUP, true);
		}
	
	};


	var removeHasPopupRole = function (element) {

		if (element.nodeType === 1) {
			element.removeAttribute(_ARIA_PREFIX + _HAS_POPUP);
		}
		
	};


	var onFocus = function (type, args) {
	
		var oEvent = args[0],
			oTarget = Event.getTarget(oEvent);	// The currently focused element

		// Modify value of the tabIndex attribute so that the currently 
		// focused MenuItem label is in the browser's default tab order.	

		if (m_oCurrentItemLabel) {
			m_oCurrentItemLabel.tabIndex = -1;
		}

		m_oCurrentItemLabel = oTarget;
		m_oCurrentItemLabel.tabIndex = 0;

	};
	

	var onBlur = function (type, args) {

		var oEvent = args[0],
			oTarget = Event.getTarget(oEvent);	// The currently focused element

		// If the focus has moved to an element on the page that is not a 
		// part of the Menu, restore the Menu to its original state 
		// so that the first item is in the browser's default tab index.
	
		m_oCurrentItemLabel.tabIndex = -1;

		m_oCurrentItemLabel = Dom.getFirstChild(this.getItem(0).element);
		m_oCurrentItemLabel.tabIndex = 0;
	
	};


	var onConfigSubmenu = function (type, args) {
			
		var oSubmenu = args[0];
			
		if (oSubmenu) {
			addHasPopupRole(Dom.getFirstChild(this.element));
		}
	
	};
	
	
	var addMenuItemRole = function (menuitem) {

		var oMenuItemEl = menuitem.element;

		// For NVDA: add the role of "presentation" to reach LI and UL
		// element to prevent NVDA from announcing the "list" role
		// as well as the menu-related roles.

		setARIARole(oMenuItemEl.parentNode, _PRESENTATION);
		setARIARole(oMenuItemEl, _PRESENTATION);


		// Retrieve a reference to the anchor element that serves as the 
		// label for each MenuItem.

		var oMenuItemLabel = Dom.getFirstChild(oMenuItemEl);


		// Set the "role" attribute of the label to "menuitem"

		setARIARole(oMenuItemLabel, _MENUITEM);


		// Remove the label from the browser's default tab order
		
		oMenuItemLabel.tabIndex = -1;


		// JAWS & NVDA announce the value of each anchor 
		// element's "href" attribute when it recieves focus, so remove  
		// the attribute so that its value isn't announced.

		oMenuItemLabel.removeAttribute(_HREF);


		// If the MenuItem has a submenu, set the "aria-haspopup" 
		// attribute to true so that the screen reader can announce 

		if (menuitem.cfg.getProperty(_SUBMENU)) {
			addHasPopupRole(oMenuItemLabel);
		}
		else {
			menuitem.cfg.subscribeToConfigEvent(_SUBMENU, onConfigSubmenu);
		}
	
	};


	var onItemAdded = function (type, args) {

		addMenuItemRole(args[0]);
	
	};


	Lang.augmentObject(MenuPrototype, {

		configUseARIA: function (type, args) {
		
			var bUseARIA = args[0],
				oParent = this.parent,
				oElement = this.element,
				sMenuRole = (this instanceof YAHOO.widget.MenuBar) ? _MENUBAR : _MENU,
				aMenuItems,
				nMenuItems,
				oMenuItem,
				oMenuItemLabel,
				sId,
				i;
	
	
			if (bUseARIA) {
		
				// Apply the "role" attribute of "menu" or "menubar" depending on the 
				// type of the Menu control being rendered.
	
				setARIARole(oElement, sMenuRole);
	

		
				// Use the "aria-labelledby" attribute to label each submenu.  This 
				// will provide the user with the name of the submenu the first time
				// one of its items receives focus.
	
				if (oParent) {
	
					sId = Dom.generateId(Dom.getFirstChild(oParent.element));
	
					setARIAProperty(oElement, _LABELLED_BY, sId);
					
				}
		
		
				// Apply the appropriate "role" and "aria-[state]" attributes to the 
				// label of each MenuItem instance.
	
				aMenuItems = this.getItems();
				nMenuItems = aMenuItems.length;

				if (nMenuItems > 0) {

					i = nMenuItems - 1;
						
			
					do {
						oMenuItem = aMenuItems[i];
						addMenuItemRole(oMenuItem);
						i = i - 1;
					}
					while ((i > -1));
						
			
					// Set the "tabindex" of the first MenuItem's label to 0 so the user 
					// can easily tab into and out of the control.
		
					if (this.getRoot() === this) {
						m_oCurrentItemLabel = Dom.getFirstChild(this.getItem(0).element);
						m_oCurrentItemLabel.tabIndex = 0;
					}
	
				}
	
				if (this === this.getRoot()) {
					this.subscribe(_FOCUS, onFocus);
					this.subscribe(_BLUR, onBlur);
				}
				
				this.subscribe(_ITEM_ADDED, onItemAdded);
		
			}	
	
		},
	
	
		initDefaultConfig: function () {
		
			fnMenuInitDefaultConfig.call(this);
		
			this.cfg.addProperty(
				_USE_ARIA, 
				{
					handler: this.configUseARIA, 
					value: (UA.gecko && UA.gecko >= 1.9) || (UA.ie && UA.ie >= 8), 
					validator: Lang.isBoolean
				}
			 );
	
		}
	
	}, "initDefaultConfig", "configUseARIA");



	// ContextMenu ARIA plugin

	var m_oTriggers = {};

	var toggleARIAForTrigger = function () {

		var sMenuId = this.element.id,
			oTrigger = this.cfg.getProperty(_TRIGGER),
			oCurrentTrigger = m_oTriggers[sMenuId],
			oElement;


		if (oCurrentTrigger) {

			if (Lang.isString(oCurrentTrigger)) {	// String id
	
				oElement = Dom.get(oCurrentTrigger);
				
				if (oElement) {
					removeHasPopupRole(oElement);						
				}
	
			}
			else if (oCurrentTrigger.nodeType === 1) {	// Element reference
				removeHasPopupRole(oCurrentTrigger);
			}				
			else if (oCurrentTrigger.length) { // NodeList or Array
				Dom.batch(oCurrentTrigger, removeHasPopupRole);
			}

		}


		if (oTrigger) {

			if (Lang.isString(oTrigger)) {	// String id

				oElement = Dom.get(oTrigger);
				
				if (oElement) {
					addHasPopupRole(oElement);						
				}

			}
			else if (oTrigger.nodeType === 1) {	// Element reference
				addHasPopupRole(oTrigger);
			}
			else if (oTrigger.length) {	// NodeList or Array
				Dom.batch(oTrigger, addHasPopupRole);
			}
				
			m_oTriggers[sMenuId] = oTrigger;

		}
	
	};


	ContextMenu.prototype.configUseARIA = function (type, args) {

		ContextMenu.superclass.configUseARIA.apply(this, arguments);

		toggleARIAForTrigger.call(this);

		this.cfg.subscribeToConfigEvent(_TRIGGER, toggleARIAForTrigger);
	
	};

}());